The present invention relates generally to pharmaceutical compositions, more particularly to pharmaceutical compositions comprising polypeptides that typically are unstable in liquid pharmaceutical formulations.
Recent advances in the development of genetic engineering technology have provided a wide variety of biologically active polypeptides in sufficiently large quantities for use as drugs. Polypeptides, however, can lose biological activity as a result of physical instabilities, including denaturation and formation of soluble and insoluble aggregates, and a variety of chemical instabilities, such as hydrolysis, oxidation, and deamidation. Stability of polypeptides in liquid pharmaceutical formulations can be affected, for example, by factors such as pH, ionic strength, temperature, repeated cycles of freeze-thaw, and exposure to mechanical shear forces such as occur during processing. Aggregate formation and loss of biological activity can also occur as a result of physical agitation and interactions of polypeptide molecules in solution and at the liquid-air interfaces within storage vials. Further conformational changes may occur in polypeptides adsorbed to air-liquid and solid-liquid interfaces during compression-extension of the interfaces resulting from agitation during transportation or otherwise. Such agitation can cause the protein to entangle, aggregate, form particles, and ultimately precipitate with other adsorbed proteins. For a general review of stability of protein pharmaceuticals, see, for example, Manning et al. (1989) Pharm. Res. 6:903-918, and Wang and Hanson (1988) J. Parenteral Sci. Tech. 42:S14.
Instability of polypeptide-containing liquid pharmaceutical formulations has prompted packaging of these formulations in the lyophilized form along with a suitable liquid medium for reconstitution. Although lyophilization improves storage stability of the composition, many polypeptides exhibit decreased activity, either during storage in the dried state (Pikal (1990) Biopharm. 27:26-30) or as a result of aggregate formation or loss of catalytic activity upon reconstitution as a liquid formulation (see, for example, Carpenter et al. (1991) Develop. Biol. Standard 74:225-239; Broadhead et al. (1992) Drug Devel. Ind. Pharm. 18:1169-1206; Mumenthaler et al. (1994) Pharm. Res. 11:12-20; Carpenter and Crowe (1988) Cryobiology 25:459-470; and Roser (1991) Biopharm. 4:47-53). While the use of additives has improved the stability of dried proteins, many rehydrated formulations continue to have unacceptable or undesirable amounts of inactive, aggregated protein (see, for example, Townsend and DeLuca (1983) J. Pharm. Sci. 80:63-66; Hora et al. (1992) Pharm. Res. 9:33-36; Yoshiaka et al. (1993) Pharm. Res, 10:687-691). Also, the need for reconstitution is an inconvenience and introduces the possibility of incorrect dosing.
While a number of liquid pharmaceutical compositions have been formulated to stabilize the biological activity of polypeptides contained therein, the degradation of polypeptides in liquid formulations continues to create problems for medical practitioners. Consequently, there is a need for additional pharmaceutical compositions comprising physiologically compatible stabilizers that promote stability of polypeptide components, thereby maintaining their therapeutic effectiveness.
Compositions comprising a polypeptide as a therapeutically active component and methods useful in their preparation are provided. The compositions are stabilized liquid pharmaceutical compositions that include a polypeptide whose effectiveness as a therapeutically active component is normally compromised during storage in liquid formulations as a result of aggregation of the polypeptide. The stabilized liquid pharmaceutical compositions of the invention comprise, in addition to a polypeptide that exhibits aggregate formation during storage in a liquid formulation, an amount of an amino acid base sufficient to decrease aggregate formation of the polypeptide during storage, where the amino acid base is an amino acid or a combination of amino acids, where any given amino acid is present either in its free base form or in its salt form. The compositions further comprise a buffering agent to maintain pH of the liquid composition within an acceptable range for stability of the polypeptide, where the buffering agent is an acid substantially free of its salt form, an acid in its salt form, or a mixture of an acid and its salt form.
The amino acid base serves to stabilize the polypeptide against aggregate formation during storage of the liquid pharmaceutical composition, while use of an acid substantially free of its salt form, an acid in its salt form, or a mixture of an acid and its salt form as the buffering agent results in a liquid composition having an osmolarity that is nearly isotonic. The liquid pharmaceutical composition may additionally incorporate other stabilizing agents, more particularly methionine, a nonionic surfactant such as polysorbate 80, and EDTA, to further increase stability of the polypeptide. Such liquid pharmaceutical compositions are said to be stabilized, as addition of amino acid base in combination with an acid substantially free of its salt form, an acid in its salt form, or a mixture of an acid and its salt form, results in the compositions having increased storage stability relative to liquid pharmaceutical compositions formulated in the absence of the combination of these two components.
Methods for increasing stability of a polypeptide in a liquid pharmaceutical composition and for increasing storage stability of such a pharmaceutical composition are also provided. The methods comprise incorporating into the liquid pharmaceutical composition an amount of an amino acid base sufficient to decrease aggregate formation of the polypeptide during storage of the composition, and a buffering agent, where the buffering agent is an acid substantially free of its salt form, an acid in its salt form, or a mixture of an acid and its salt form. The methods find use in preparation of the liquid pharmaceutical compositions of the invention.